The Avro 504 was a biplane aircraft the first flew September 18, 1913. A few of the aircraft were bought by the Royal Flying Corps and the Royal Naval Air Service prior to the start of WWI and were taken to France when the war started. The 504 was the first airplane to strafe troops on the ground and the first to make a bombing raid over Germany. It was also the first Allied aircraft to be shot down by the Germans on August 22, 1914. The 504 was soon obsolete as a front line aircraft and was extensively used as a trainer with production during WWI totaling 8,970 aircraft and continuing for 19 more years for a total production run of over 10,000. This makes the Avro 504 the most produced aircraft of any kind that served in World War I. After the end of the war huge numbers of Avro 504s were available for sale for both civil and military use. More than 300 504Ks were placed on the civil register in Britain alone and the 504 continued flying until well into the 1930s. The Avro 504 was flown by Argentina, Australia, Western Australian Airways, Belgium, Brazil, Canada, Chile, China, Denmark, Estonia, Finland, Greece, Guatemala, British India, Iran, Ireland, Japan, Federated Malay States, Mexico, Mongolia, Netherlands, New Zealand, Norway, Peru, Poland, Portugal, Russian Empire, South African Air Force, Soviet Union, Kingdom of Spain, Sweden, Switzerland, Siam, United Kingdom, United States, Uruguay, Qantas Airlines and hundreds of barnstormers. There are still several flyable Avro 504s around the world almost 100 years after the first flight. This model shows an Avro 504 K of the Estonian Air Force in 1920.